Pulse jet propulsion device and method of operating same



March 13, 1962 BECK ET AL 3,024,597

PULSE JET PROPULSION DEVICE AND METHOD OF OPERATING SAME Filed July 16, 1956 2 Sheets-Sheet 1 U 60A 25A 14 a4 86 84 60B 25B j 25 INVENTORS NIELS J'. BECK t 90 MM W "HIWHM 83 JOSEPH IR. 72' WWI 1 IIIWHHHIHIIP 83'86 HAL UNDERFELT March 13, 1962 N. J. BECK ETAL 3,024,597

PULSE JET PROPULSION DEVICE AND METHOD OF OPERATING SAME Filed July 16, 1956 2 Sheets-Sheet 2 INVENTORS E 7 26 65 JOSEPH E. LEACH IR.

72 HAL R. LINDERFELT ATTORNEYS United States Patent Ofiice 3,024,597 Patented Mar. 13, 1962 PULSE JET PRQPULSION DEVICE AND METHGD 9F GPERATING AME Niels J. Beck, 1336 Minot St, Anaheim, Calif; Joseph E. Leach, Jr., 3331 17th St., Santa Monica, Calif.; and Hal R. Linderfelt, 113% Navy se, Los Angeles, Calif.

Filed July 16, 1956, Ser. No. 597,998 '7 Claims. (Cl. 6il35.6)

This invention has to do with jet propulsion devices and more particularly with pulsing-type internal combustion engines in which the products of combustion are exhausted into a liquid medium, either for pumping the liquid or for propelling an object with relation'to the liquid by reaction.

An object of the invention is to provide a novel and improved pulse jet liquid propulsion device suitable for marine propulsion or the pumping of liquids.

While we are aware that pulsing internal combustion engines have been devised for marine propulsion and the like, so far as we know, none of the prior devices has been successful. This appears to be due to the fact earlier devices have one or more of the following disadvantages: premature ignition of the charge resulting from the employment of carburization of the fuel; inability to operate under static condition of the liquid into which the products of combustion are expelled, as, for example, the failure of the device to operate as a marine propulsion unit unless the boat is in motion; dependence upon an ignition system for timing; and extreme inefficiency under the best operating conditions. One of the major disadvantages of known devices appears to be due to faulty design of the propulsion unit through which the combustion gases are expelled, resulting in inability of the device to draw into the combustion chamber sufficient air to provide proper combustion.

It is therefore a particular object of the invention to provide a pulse jet type internal combustion propulsion device which is so designed and proportioned as to be relatively efiicient for liquid propulsion or the like and which does not have the above-noted and other disadvantages of prior devices.

Another object is to provide a device in which the ratio of the volume of the combustion chamber to that of the volume of the propulsion unit and in which the ratio of the valve inlet area for the combustion chamber to the valve inlet area of the propulsion unit are such as to result in a relatively efiicient pulsing device which will operate on a regular pulsing cycle independently of a timed ignition means.

A further object is to provide a novel and improved propulsor or propulsion unit into which the products of combustion are delivered and expanded to move the liquid therefrom and to provide in such a unit adequate means for permitting rapid filling of the unit with liquid at the appropriate time period of the cycle of operation.

A still further object is to provide a propulsion unit through which the gases of combustion are discharged which is so designed as to permit the gases to fully expand before leaving the unit to thereby maintain a negative pressure in the combustion chamber for a sufficient time to permit an ample charge of air to enter the combustion chamber.

Yet another object is to provide a simple device which is relatively inexpensive to manufacture, economical to operate and is of light weight.

These and other objects will be apparent from the drawings and the following description. Referring to the drawings:

FIG. 1 is a diagrammatic view of a device embodying the invention;

FIG. 2 is a sectional elevational view of the combustion chamber means and propulsion unit of the device of FIG. 1;

FIG. 3 is an inverted sectional view on line 33 of FIG. 2;

FIG. 4 is a sectional view on line 4-4 of FIG. 2, but on a larger scale;

FIG. 5 is a sectional view on line 5-5 of FIG. 2, but on a larger scale; and

FIG. 6 is an enlarged detail sectional view of a portion of the propulsion unit on line 6-6 of FIG. 5.

More particularly describing the invention, in FIG. 1 there is diagrammatically illustrated a pulsing-type internal combustion engine for use in marine propulsion. It is contemplated that the apparatus shown would be mounted in or upon a boat (not shown) and may take the form of what is commonly termed an outboard motor. Thus reference L indicates liquid which may be a body of water. The device comprises a combustion unit, designated 11, and'having a combustion chamber 12, a propulsion unit or propulsor 14 located below the surface of the liquid, a tailpipe 15 connecting the combustion unit and propulsor, and a fuel supply means 17. The combustion unit includes a casing 20 which defines the aforementioned combustion chamber 12. A spark plug 21 is shown projecting into the chamber and provided with a wire 22 which may lead to a suitable source of interrupted high tension electric current. The combustion chamber is in open communication with the interior of propulsion chamber 25 of the propulsor 14 through the medium of the tailpipe 15. For both practical and theoretical purposes the interior of the tailpipe may be considered as an extension of the combustion chamber.

The chamber 25 in the propulsor is shown as annular and as provided with a plurality of inwardly opening check valve rings 26 and 27 throughout a substantial portion of its length for the purpose of rapidly admitting liquid to the interior at the proper portion of the pulse cycle. The construction of the propulsor will be described in more detail later.

It is a particular feature of our invention that we provide for the independent introduction of air and fuel into the combustion chamber. By way of illustration we have shown a clover-like reed valve member, designated 28, mounted against the upper wall 20' of the combustion chamber housing. This valve in its normal position serves to cover or close a plurality of circumferentially disposed air inlet ports 29.

For the purpose of introducing fuel into the combustion chamber we provide a closed fuel tank, designated 30, connected to the combustion chamber by a fuel supply conduit 31. The latter may include a check valve 32. Conduit 31 is shown communicating with the interior of an outermost chamber 34 in a fuel vaporizer 35. The vaporizer includes a central threaded bushing 38 shown threadedly mounted in the upper wall 20' of the combustion chamber. Secured to this is a nut 39, an inner cage 40 and an outer housing 41. A cap 42 closes the outer housing, being fitted with a gland at 43, and is provided with a threaded opening at 44 to adjustably receive a valve stem 46. The latter has an inner valve element 48 adapted to seat at the outer end of bus-hing 38 and a second valve element 50 adapted to seat against the end of cage 40 to close the opening 40'. The construction provides an outer chamber 34 and an inner chamber 45 through which the fuel must pass in turn before entering the combustion chamber, thus affording ample time for a liquid fuel to be vaporized before entering the combustion chamber, once the vaporizer has become heated by firing of the device.

It is a particular feature of our invention that We continually feed fuel to the combustion chamber under pressure. We accomplish this, in the case of liquid fuel, by pressurizing tank 30 through a pressurizing conduit 52 which connects and establishes communication between the interior of the fuel tank and the interior of the combustion chamber. A check valve 53 is provided in the line and additionally a pressure relief valve is provided as indicated at 54. With this construction, fuel is continually fed to the combustion chamber eXcept during the portion of the combustion cycle when the pressure in the combustion chamber equals or is greater than the effective fuel feed pressure.

Any suitable source of high voltage electrical current (not shown) may be provided in conjunction with the spark plug and this need only be used to start the engine and to keep it running until it becomes warmed up, since we may provide a glow plug device or re-igniter 56 for the purpose of igniting the combustible charge once this has become hot. The glow plug or re-igniter may take the form described in United States Letters Patent 2,396,- 368, although other forms of device are suitable.

While we have shown and described apparatus for storing and feeding a liquid fuel, We also contemplate that gaseous type fuels may be used such as would supply their own pressure for feed purposes. In such cases the pressurizing conduit 52 can be eliminated, or it may be retained and closed by a valve 58, shown in broken lines in FIG. 1.

In the functioning of the unit it is of paramount importance that the gases of combustion have an opportunity to fully expand in the propulsion unit before escaping therefrom in order to induce, in conjunction with the moving mass of liquid propelled by the gases, a negative pressure condition in the combustion unit and maintain this for sutficient time to permit a large quantity of air to be drawn into the combustion chamber for the next cycle. It is also important that liquid be permitted to enter the propulsion unit rapidly at the appropriate time in the cycle. This is accomplished by the propulsion unit 14. The unit comprises a forward section 60A and a rear section 60B which define the chamber 25. The forward section 60A provides an annular chamber section 25A while the rear section 60B provides an open-ended chamber section 25B forming a continuation of the section 25A.

The chamber 25A in the forward section of the propulsion unit is defined by a plurality of axially overlapping flexible valve rings comprising a series of inner rings 26 and a series of outer rings 27. Each outer ring includes a metal mounting ring 61 (FIG. 6) having a plurality of circumferentially spaced apertured tabs 62. A flexible conoidal ring section 64, which may be made of a suitable synthetic rubber or plastic, is bonded to the mounting ring. In a similar manner each inner valve ring includes a metal mounting ring 65 having apertured tabs 66, and a flexible ring section 67 bonded to the mounting ring.

The various valve rings are mounted in axially overlapping relation with the mounting rings 61 and 65 spaced axially along rods or bolts comprising an outer series of rods 71 and an inner series 72. Tubular spacers 73 are. employed between the mounting rings.

The rods 71 and 72 extend through the end plate 78 which closes the forward end of the propulsion unit chamber and terminate in heads 71', 72', respectively, on the outer side of a nosing 79. One of the rods terminates forwardly of a tailpipe mounting plate 81, to be described later. At their other ends, the rods 71 and 72 serve to secure the rear section of the propulsion unit which comprises an inner cylindrical shell 83 and a concentrically disposed outer cylindrical shell 84, the two shells defining the aforementioned chamber 25B. The shells are flanged at 83 and 84' and rods 71 and 72 extend therethrough, being secured by nuts 86.

The structure is braced by an internal partitioning means comprising the assembly 90 formed of four plates 91 each of which is bent to form two corresponding sections 92 disposed at right angles to each other. The four plates may be secured by spotwelds (not shown). The ends of the plates are each provided with a quarter round section 93 so that each pair of adjacently disposed plate sections forms a semi-circular seat 95 extending longitudinally of the propulsion unit and adapted to fit against and partially receive the spacers 73 about one of the rods 72.

The tailpipe 15 terminates at its lower end in a flange 15' which is secured by cap screws 97 to a mounting plate 81 secured in a cutaway portion of the propulsor by means of cap screws 98 and 93'. The ends 64 of rings 64 are secured between the mounting plate 81 and a plate 99.

In the operation of the device, assuming that a liquid fuel is used, this may be pressurized originally by means of a hand pump or other suitable means. The fuel feed valve 46 is opened to admit fuel to the combustion chamber 12 which contains air or other oxidizer. The spark plug is caused to operate with the result that an explosion occurs when the mixture of air and fuel reaches explosive proportions. The gaseous products of combustion expand down the tailpipe and into the propulsor forcing the liquid therein out the rear of the propulsor. During this action the pressures in the propulsor are higher than those in the surrounding liquid and, consequently, the valve rings in the forward section of the propulsor close. As a result of the full expansion of the gases and the inertia of the moving mass of liquid, a condition of negative pressure develops in the propulsor and in the combustion chamber. When the pressure falls below atmospheric in the combustion chamber, air inlet valve 28 opens and a charge of air rapidly enters the combustion chamber. Liquid also begins to enter the propulsor through the valve rings forming the forward section 25A of the propulsor chamber 25 and rapidly fills the propulsor.

The chamber 25B in the rear section, by reason of the fact that it is formed by unbroken Walls, provides space for the rearwardly moving explosion gases enabling the same to fully expand before leaving the propulsor. This serves to prolong the condition of negative pressure sutliciently to result in an ample charge of air being drawn into the combustion chamber and in the propulsor chamber rapidly filling with liquid. Since fuel is substantially continually entering the combustion chamber, an explosion soon occurs and the cycle is repeated. Once the reigniter has become hot, the electrical ignition means may be discontinued. Also, successive explosions serve to maintain the fuel tank pressurized.

When using liquid fuel, in the initial stages of operation, at each explosion the liquid fuel may be forced back part way toward the fuel tank, creating a relatively long time lag before the fuel again enters the combustion chamber. As the fuel vaporizer becomes heated, and the fuel vaporized therein, this occurs to a much less degree, or not at all, and the speed of firing increases. There is some time lag in the introduction of fuel, however, to prevent premature ignition.

We have found that for eificient operation the ratio of the volumetric capacity of the combustion chamber (which includes the tailpipe) to the volumetric capacity of the propulsion chamber should be such as to permit substantially complete expansion of the gases of combustion before leaving the propulsor. Also, the ratio of the area of the air inlet ports of the combustion chamber to the area of the liquid inlet passages of the propulsor should be preferably of the order of the ratio of the square root of the density of air to the square root of the density of the liquid in which the propulsor is immersed.

While we have shown and described a specific form of our invention, we contemplate that various changes and modifications can be made therein without departing from the invention, the scope of which is set forth by the claims, which follow.

We claim:

1. A propulsion unit adapted to be submerged in liquid and adapted to form part of a pulse jet device including a combustion chamber, comprising a supporting frame, a plurality of flexible, ring-like walls mounted on said frame in axially overlapping relation and defining a propulsion chamber, said walls being secured adjacent one margin only whereby to permit the same to act as inwardly opening check valves for the chamber, means closing one end of said chamber, the opposite end of said chamber being open, said propulsion unit having an opening in the region of its closed end for admitting expanding gases of combustion issuing from said combustion chamber.

2. A propulsion unit adapted to be submerged in liquid and adapted to form part of a pulse jet device including a combustion chamber, comprising a supporting frame, a plurality of flexible ring-like walls mounted on said frame in axially overlapping relation and defining a propulsion chamber, said walls being secured adjacent one margin only whereby to permit the same to act as inwardly opening check valves for the chamber, means closing one end of said chamber, the opposite end of said chamber being open, said propulsion unit having an opening in the region of its closed end for admitting expanding gases of combustion issuing from said combustion chambers, and imperforate casing means at the open end of said propulsion chamber attached to said frame and forming an openended extension of the chamber formed by said valve rings.

3. A propulsion unit adapted to be submerged in liquid and adapted to form part of a pulse jet device including a combustion chamber, comprising a supporting frame means, an outer series of axially overlapping flexible ringlike walls, an inner series of axially overlapping flexible ring-like walls concentric with said outer series, said inner and outer series of walls being secured at one margin only to said supporting frame means and cooperating to define an annular propulsion chamber, and means closing one end of said chamber, the opposite end of said chamber being open, said propulsion unit having an opening in the region of its closed end for admitting expanding gases of combustion issuing from said combustion chamber.

4. A propulsion unit as set forth in claim 3 in which the individual walls of said inner and outer series are normally conoidal and inclined inwardly of the propulsion chamber leaving annular openings between said walls.

5. In a pulse jet propulsion device adapted to exhaust into a liquid and having a combustion chamber with check valve-controlled air inlet means adapted to be located in the atmosphere above the liquid, means for supplying fuel to the combustion chamber, and means for igniting a combustible charge in said chamber, a propulsor unit adapted to be submerged in the liquid and providing an elongated annular propulsion chamber closed at its forward end and open at its rearward end, an upright tailpipe providing open unrestricted communication between the combustion chamber and the forward end of said propulsion chamber, said propulsor unit being characterized by having liquid inlet openings in its inner and outer walls throughout a major portion of its length rearwardly of its forward end, and check valve means controlling said openings.

6. A pulse jet propulsion device as set forth in claim 5 in which the ratio of the area of the air inlet means of the combustion chamber to that of the area of the liquid inlet means of the propulsion chamber is of the order of the ratio of the square root of the density of air to the square root of the density of the liquid for which the propulsor unit is designed.

7. A pulse jet propulsion device as set forth in claim 5 in which the liquid inlet openings extend for approximately two-thirds the length of the propulsion chamber and in which said propulsion chamber is defined by imperforate walls throughout the remaining portion of its length to the open end thereof.

References Cited in the file of this patent UNITED STATES PATENTS 964,574 Sodeau July 19, 1910 1,008,871 Sodeau Nov. 14, 1911 1,493,753 Kolerofr May 13, 1924 2,412,825 McCollum Dec. 17, 1946 2,463,820 Stafford et al. Mar. 8, 1949 2,516,910 Redding Aug. 1, 1950 2,522,945 Gongwer et al Sept. 19, 1950 2,523,378 Kollsman Sept. 26, 1950 2,683,963 Chandler July 20, 1954 2,684,571 Wright July 27, 1954 2,738,334 Tenney et a1 Mar. 13, 1956 FOREIGN PATENTS 558,113 Germany Sept. 1, 1932 841,552 Germany June 16, 1952 574,552 Great Britain Jan. 10, 1946 

